Japanese patent application publication No. 2007-35885 discloses a prior lighting device. The prior lighting device comprises a combination of an LED chip and a phosphor, whereby the prior lighting device outputs light having a desired color. The desired color of light is, such as, a white light.
The prior lighting device comprises an LED chip, a mounting substrate, a light transmissive sealing member, a first color conversion member, and a second light conversion member. The mounting substrate is realized by a ceramic substrate. The mounting substrate is provided for mounting the LED chip. The light transmissive sealing member is made of a light transmissive sealing material such as silicone resin. The light transmissive sealing member is shaped to have a hemisphere shape, whereby the light transmissive sealing member is cooperative with a mounting surface of the mounting substrate to seal the LED chip. The first color conversion member comprises a first light transmissive member. The first light transmissive member is made of a first light transmissive material such as a silicone resin and a phosphor. The phosphor is configured to be excited by the light which is emitted from the LED chip, whereby the phosphor emits the light which has a wavelength which is longer than a wavelength of the light which is emitted from the LED chip. The first color conversion member is shaped to have a dome-shape. The first color conversion member is attached to the mounting substrate such that the first color conversion member is located at a side of the light output surface of the light transmissive sealing member. The second color conversion member comprises a second light transmissive member. The second light transmissive member is made of a second light transmissive material and a second phosphor. The second light transmissive material is such as a silicone resin. The second phosphor is configured to be excited by the light which is emitted from the LED chip, whereby the second phosphor emits the light which has a wavelength which is longer than the wavelength of the light which is emitted from the LED chip. The second color conversion member is shaped to have a dome-shape. The second color conversion member is disposed on the mounting substrate so that a light transmissive layer is interposed between the first color conversion member and the second color conversion member. The LED chip is realized by a blue light emitting diode chip (blue LED chip). The first phosphor has a first optical absorptance with respect to the light which is emitted from the LED chip. The second phosphor is realized by a phosphor which has a second optical absorptance with respect to the light which is emitted from the LED chip. The second optical absorptance is greater than the first optical absorptance.
In the above lighting device, both the first color conversion member and the second color conversion member are shaped to have the dome shapes. Therefore, this configuration makes possible to prevent a color unevenness of the light. In addition, the second phosphor has the second optical absorptance which is greater than the first optical absorptance of the first phosphor. Therefore, it is possible to improve quantum efficiency, whereby the efficiency of a light extraction to an outside of the lighting device is enhanced.